Karankawa Indian Language

Karankawa is an extinct language of the East Texas coast.
Karankawa is generally considered a language isolate (a language unrelated to any other known language), though some linguists have tried
to link it to the Coahuiltecan, Hokan,
or even Carib language families.
Since few records of the language remain and those records contain many discrepancies, this question will probably never be answered
conclusively. The Karankawa language has not been spoken since the 1850's.